I guess some might find this useful: To make the long story short - I was setting up my router with OpenWrt to share the internet, and connected the wrong power supply unit that provided 7.5 instead of 5 volts. The router is ok – there’s a good stepdown converter onboard, while the usb host is directly powered by what comes from power supply. So, that’s 2.5 volts overvoltage.The modem got totally screwed: Blink and it’s dead. So I took the screwdriver and disassembled it and found a way to fix.

I realize companies try to make things as cheap and disposable as possible these days, but would it be too much to ask for a $100 piece of hardware to have a voltage regulator circuit that costs less than a cent when bought in the same bulk orders as everything else on the board?

How many times have you fried something by putting the batteries in the wrong way and thought "would it have killed them to add a diode?"